Thermodynamic Modeling of Mutual Solubilities in Gas-Laden Brines Systems Containing CO2, CH4, N2, O2, H2, H2O, NaCl, CaCl2, and KCl: Application to Degassing in Geothermal Processes

Salaheddine Chabab,François Contamine,Jean Paul Serin,Marion Ducousso,Marie Poulain,Pierre Cézac,José Lara Cruz

doi:10.3390/en14175239

Salaheddine Chabab, François Contamine + Show 5 more

Open Access

https://doi.org/10.3390/en14175239

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Journal: Energies	Publication Date: Aug 24, 2021
Citations: 7	License type: CC BY 4.0

Affiliation: Université de Pau et des Pays de l'Adour

Abstract

With the growing interest in geothermal energy as a renewable and sustainable energy source, nowadays engineers and researchers are facing technological and environmental challenges during geothermal wells’ operation or energy recovery improvement by optimizing surface installations. One of the major problems encountered is the degassing of geothermal brines which are often loaded with dissolved gases, resulting in technical problems (scale formation, corrosion, reduced process efficiency, etc.) and environmental problems through the possible emission of greenhouse gases (CO2, CH4 and water vapor) into the atmosphere. In this work, a method to predict, from readily available information such as temperature and GLR, the bubble point pressure of geothermal fluids as well as the GHG emission rate depending on the surface conditions is presented. This method is based on an extended version of the Soreide and Whitson model with new parameters optimized on the solubility data of several gases (CO2, CH4, N2, O2 and H2) in brine (NaCl + CaCl2 + KCl). The developed approach has been successfully used for the prediction of water content of different gases and their solubilities in different types of brines over a wide temperature and pressure range, and has been applied for the prediction of bubble point pressure and GHG emissions by comparing the results with available industrial data of geothermal power plants including the Upper Rhine Graben sites.

Highlights

The development of renewable energy is one of the key strategies for contributing to the decrease of greenhouse gas (GHG) emissions [1]
The geothermal resource heat is retrieved with an Enhanced Geothermal System (EGS) [3], which boosts rock porosity to extract the proper amount of fluid for heat recovery [5]
The asymmetry of the binary interaction parameters used in the Soreide and Whitson Equation of State (EoS) permits one to overcome the lack of “flexibility” of the symmetrical approach concerning the distinct representation of the liquid and vapor phases by using specific parameters for each phase

Summary

Introduction

The development of renewable energy is one of the key strategies for contributing to the decrease of greenhouse gas (GHG) emissions [1]. Depending on the depth of the reservoir containing the geothermal fluid, two applications are distinguished: shallow geothermal and deep geothermal [3,4]. In some deep geothermal reservoirs, ground permeability is too low to properly extract the fluid from its well. The geothermal resource heat is retrieved with an Enhanced Geothermal System (EGS) [3], which boosts rock porosity to extract the proper amount of fluid for heat recovery [5]. EGS projects are ongoing in Australia, France, Germany, the United Kingdom and the United States. Their development stages are different from one country to another. While some of them are at plant construction and well drilling phases, such as those in Australia and the United Kingdom, others are commercial-scale plants, such as those in French territory [5,6,7]

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